As the calendar flipped to October this week, the attention of commercial and recreational catchers of oysters turned to the tasty bivalves, as the season officially began Tuesday.

Of course, the still-warm water continues to afford the opportunity to haul in some meaty, late-season hard crabs, but the Maryland Department of Natural Resources wants those who enjoy the fruits of our waterways to know about the season limits for oyster harvesting.

This season, by DNR’s orders, there will be no commercial harvesting on Wednesdays, and temporary closures to wild harvesting in certain areas where there is a low abundance of oysters, low natural spat set or where spat-on-shell plantings are being protected, including some areas north of the Chesapeake Bay bridge.

Also, the recreational harvest will be limited to three days a week — Tuesdays, Fridays and Saturdays only — with no oystering after noon and a 50% reduction in harvest limits. The details were issued by public notice and are available on DNR’s website, dnr.maryland.gov, under “Fisheries” and then “Shellfish Closures/Openings.”

In these times of preservation and restoration efforts, this is a good idea. DNR scientists expect that these measures will result in approximately a net 26% reduction in the state’s oyster harvest. These revised regulations will be combined with other measures outlined in Maryland’s new Oyster Management Plan with the goal of ultimately increasing oyster populations and garnering a sustainable oyster fishery in the next eight to 10 years.

“It is important that we begin implementation as soon as possible,” DNR Secretary Jeannie Haddaway-Riccio said in a release. “If we combine sustainable fishing practices with other measures such as strategic investment, habitat restoration and sanctuaries, the result will be real, long-term solutions.”

Of course, fluctuations in the oyster population are caused by many factors, such as nutrient pollution, disease, harvest pressure and freshwater flows. Although this summer and early fall have been quite dry, the heavy rains of the past two years have introduced large amounts of fresh water and greatly reduced salinity in portions of the bay, impacting oyster habitats and their reproduction.

These latest DNR oyster regulations can hopefully dovetail with federal efforts to help. The latest is $800,000 in funding to aid habitat restoration work on the St. Mary’s River, as well as other sites in Maryland like the Little Choptank, Tred Avon and Manokin rivers and Harris Creek. And that’s part of an overall $37 million federal investment.

This is critical, since DNR estimates there were 300 million mature oysters in the state’s portion of the bay in 2018 — down from 600 million in 1999. Those five waterways are tributaries of the bay, where scientists are working toward a goal of 50 oysters per square meter.

And despite their well-earned reputation as one of nature’s most efficient and prodigious water filters, oysters can’t block everything. A recent report by the Bay Journal News Service said a new study found some Chesapeake oysters have apparently been ingesting ingredients found in sunscreen from the water and sediment around them.

A team led by researchers from the University of Maryland, Baltimore County found ultraviolet ray-filtering chemicals used in commercial sunscreens, along with antibiotics and endocrine-disrupting hormones, in bay water, bottom sediments and oyster tissue taken from the mouth of the Chester River and three locations on the lower Eastern Shore. The study was produced in collaboration with researchers from the University of Maryland School of Medicine, the U.S. Forest Service and DNR.

“Are there environmental impacts on oysters? We don’t know that,” said Lee Blaney, the study’s lead author and an associate professor of chemical, biochemical and environmental engineering at UMBC. But “we figure it’s better to get out ahead of the issue” and determine if these contaminants are accumulating in sediment or living creatures and warrant further investigation.

Of course, no one’s suggesting discontinuing the use of sunscreen, but it’s just another reminder that chemicals we put into everyday use can have long-lasting effects.

So celebrate the oyster this month. The annual Blessing of the Fleet celebration tomorrow and Sunday recalls a time when watermen and oysters were much more plentiful. And later this month, the U.S. Oyster Festival returns to the county fairgrounds, with its national cooking and shucking contests. If those events should inspire you to go tonging, just remember to try your hand only on Tuesday, Friday and Saturday mornings.